MAKE_ROOM_FOR_BLOCK

I develop scripts and plugins for AfterEffects.
As the data gets bigger, the processing slows down dramatically.
Attaching with C ++ and looking at the output
The message about MAKE_ROOM_FOR_BLOCK seems to be frequent and related to the slowness.

Please tell me how to:
1. Meaning of MAKE_ROOM_FOR_BLOCK message
2. How to know the situation in advance
3. Also, how to prevent it from appearing